Conventionally, a polycrystalline silicon film or an amorphous silicon film has typically been adopted as a channel layer of a thin film transistor, which is an example of an electronic device. However, when a polycrystalline silicon film is used, electron scattering at the polycrystalline grain boundary limits electron mobility, so as to cause variation in transistor property. When an amorphous silicon film is used, electron mobility is very low and an element tends to deteriorate with time, so as to cause extremely low element reliability. In this regard, an oxide semiconductor has been attracting interests, which is higher in electron mobility than an amorphous silicon film and has less variation in transistor property than a polycrystalline silicon film. Moreover, not only an oxide semiconductor, but also an oxide conductive material or an oxide insulator made of an oxide is an essential technical element for realization of an electronic device made of only an oxide, for example, and thus is attracting very high industrial interests.
There has been recently an active attempt to produce an electronic device on a flexible resin substrate in accordance with a low-energy production process such as a printing method. There is an advantage that a semiconductor layer can be patterned directly on a substrate in accordance with a printing method or the like and no etching step is thus required for patterning.
As disclosed in Patent Documents 1 to 3, there has been an attempt to produce a coated flexible electronic device including a conductive polymer or an organic semiconductor, for example.